New faster list iterators
Change list code to be simpler and faster
Optimize count(distinct)
New error messages for UNION
Make create_tmp_table more general to be usable by UNION
fixed concurrency bug with a very quickly disconnecting client -
the client could disconnect and delete thd before pthread_create
could write to &thd->real_id
sql/sql_list.h
while tracking down the bug, made new/delete go through my_malloc/my_free
for ilink - did not help, but this is better anyway - cleaner exit with a message in
out of memory codition at least.